The proposed research focuses on the formation of intimal hyperplasia, a crucial problem affecting all cardiovascular interventions. Intimal hyperplasia or restenosis results from the pathologic proliferation and migration of smooth muscle cells at the site of vascular injury, caused by surgery or angioplasty. Patients served by the Veterans Administration have a higher incidence of these procedures than the general population. A major limitation of current therapies is that they target not only the vascular smooth muscle cells, but also the beneficial endothelial cells of the injured vessel. The ideal therapy would inhibit vascular smooth muscle cell proliferation and migration without negatively impacting the endothelium. We have identified a promising candidate, the myristolated alanine-rich C kinase substrate (MARCKS), a membrane bound protein that translocates to the cytosol upon phosphorylation by protein kinase C. Previous work by the candidate has demonstrated that MARCKS knockdown results in decreased vascular smooth muscle cell migration and proliferation without affecting endothelial cells. The central hypothesis of this application is that MARCKS represents a cell specific target for modulation of vascular smooth muscle cell proliferation and migration. Currently, the mechanisms by which MARCKS induces vascular smooth muscle cell proliferation and migration are unknown, and the goal of these studies is to elucidate these mechanisms. The specific hypotheses to be tested are: 1) that MARCKS regulates vascular smooth muscle cell proliferation by up- regulation of the cell cycle inhibitor, p27kip1 2) that MACRKS modulates cell migration by disrupting cellular actin organization and 3) that MARCKS knockout in vivo will prevent intimal hyperplasia formation, but allows normal reendothelialization after arterial injury. The proposed studies will elucidate the molecular mechanisms responsible for the differential effects of MARCKS inhibition on smooth muscle cells and endothelial cells noted in the applicant's prior data. These studies will form the scientific basis for smooth muscle cell specific antiproliferative therapy, a significant, unmet need in cardiovascular interventions. The pathways and mechanisms elucidated in the proposed studies will also reveal other potential molecular targets for smooth muscle cell specific antiproliferative and antimigratory therapy. The candidate, Dr. Monahan, is a vascular surgeon at the Baltimore Veterans Administration Medical Center, and an Assistant Professor of Surgery at the University of Maryland School of Medicine. He has previously studied the genetics and molecular mechanisms of intimal hyperplasia, and has numerous publications, including some preliminary data for this proposal. Dr. Monahan's long-term career goal is become an independent clinician-investigator. In order to carry out this research, Dr. Monahan proposes a career development award that is designed to provide him with laboratory skills in several key areas by working with a team of distinguished co-mentors in addition to his mentor, Dr. Wang: the generation and management of complex mouse mutants (Dr. Strickland); the analysis of actin and small GTPase regulation of migration (Dr. Zhan); and the generation of an in vivo model of re-endothelialization (Dr. Sarkar). Dr. Monahan will also receive additional training in laboratory management, research ethics, and scientific communication. These skills are crucial not only to the proposed research, but to Dr Monahan's long term goal: to become an independent clinician-investigator. In summary, the Career Development Award (CDA-2) would provide Dr. Monahan with the research experience, mentoring and skills required to a leader in this important area of translational research. Importantly, Dr. Monahan is fortunate to be part of a larger vascular biology research team, whose support will contribute to his ability to achieve his long-term goal of performing clinically relevant, basic science research.